The wheelchair is a valuable device for assisting disabled individuals in transporting themselves from one location to another. The most common type of wheelchair in use today is that fashioned from two substantially rigid side frames each including a large main wheel and a smaller front wheel, and joined together by a collapsible brace, a canvas seat and backrest. This wheelchair type can be easily folded for storage, such as in the trunk of an automobile. The conventional wheelchair is designed with a low center of gravity so as to enhance the stability and safety of the wheelchair. As a result, such a wheelchair is provided with a relatively low level seat position, generally lower than that of a typical chair. While such a design enables disabled individuals to more efficiently access and exit the wheelchair, move about their living and working space, sit at a table or desk and the like, this design has inherent disadvantages.
One significant drawback associated with the standard wheelchair described above is that the reach of the individual user of the wheelchair is severely limited. Countertops, stovetops, sinks and washbasins, cupboards, workbenches, grocery shelves and other high surfaces generally are either inaccessible to one confined in a wheelchair or are only partially accessible. For instance, a disabled individual using a wheelchair may be able to cook on a stove, but the top of the stove is at the eye level of that individual. The inability of the wheelchair user to attain a sufficient height also poses other problems. For example, in conversation, the wheelchair user is placed in the uncomfortable position of always having to look up to persons who are standing, rather than being able to engage standing persons at eye level.
Numerous attempts have been made in the prior art to elevate or raise the person sitting in the wheelchair. For example, wheelchairs with means to elevate the seat portion, as shown in U.S. Pat. Nos. 1,219,834, 2,578,382, 2,982,336 and 3,215,469 have been proposed. However, with such designs, the ability to collapse and fold the wheelchair for easy storage has been abandoned.
British Patent 922,175 shows a collapsible wheelchair having a seat portion which is elevated by a hydraulic ram. However, the seat frame work and hydraulic ram must be removed prior to folding the wheelchair.
U.S. Pat. No. 3,985,389 to Bonfield discloses another elevating means for raising an entire wheelchair, said means comprising a pair of extendable frameworks which are secured to the sideframes of a wheelchair and a hydraulically actuated lifting means. In operation, the hydraulic lifting means causes the pair of frameworks to extend downwardly and engage the ground while elevating the entire wheelchair. As the frameworks are secured to the sideframes, the modified wheelchair remains collapsible and foldable for storage.
U.S. Pat. No. 4,886,288 to Dysarz provides a wheelchair which can be elevated on four legs that extend from beneath the wheelchair to a position outside of the wheel base of the wheelchair. The elevating means is accomplished by the use of hydraulic or pneumatic pressure reacting on the cylinders that form the four legs.
While much progress has been made in developing wheelchairs which can be elevated by a person confined to a wheelchair, such wheelchairs still do not satisfy the varied and special needs of the wheelchair user. For example, although such devices assist the wheelchair user in reaching certain items, the wheelchair must be lowered to its pre-elevated state when it is desired to move to a different location. Raising and lowering the wheelchair can be especially cumbersome on the user while performing certain everyday tasks, such as grocery shopping, moving about a kitchen in order to prepare a meal, and the like. For example, the wheelchair user who is grocery shopping must elevate the wheelchair to reach an item on a high shelf, lower the wheelchair to its normal position, move down the grocery aisle and once again elevate the wheelchair to reach an item on a high shelf. This continuous raising and lowering of the wheelchair in order to complete such an elementary chore, is not only time-consuming, but also is discouraging to the wheelchair user attempting to achieve a level of independence.
To date, there have not been any great strides in developing a wheelchair which can be elevated and which can be safely and efficiently motivated by the user while in its elevated position. U.S. Pat. No. 4,193,147 to Fischer provides a cantilevered lifting and transporting device which may be automatically or manually converted from a chair to a stretcher or vice versa. Although the device is raised and lowered by a hand-cranked screw and nut combination, it is more akin to a hospital or nursing home transport vehicle than a conventional wheelchair which has elevating means. Indeed, the Fischer device is not collapsible and, as shown, cannot be motivated by the user.
U.S. Pat. No. 4,477,117 to Higgs offers a wheelchair having means to elevate the seat and back portion relative to the main frames of the wheelchair. Higgs provides a specially constructed side frame having an elevating device, such as a "Saginaw" jacked screw, such that each side frame is elevated relative to the main frames which carry the wheels of the wheelchair. In this manner, the side frames and the seat and back portions raise together as a unit, along with the cross struts to maintain the stability of the wheelchair. However, the arm rests and foot rest are not elevated and have to be manually adjusted once the wheelchair is elevated. As the wheels remain at ground level, it appears possible that the wheelchair could be motivated while elevated, although the stability of the elevated wheelchair may be an impediment to free mobility. Further, it is unclear and doubtful whether the individual confined to the wheelchair could easily motivate a manual wheelchair given the fact that in Higgs, it is the individual who has been elevated up and away from the main driving wheel. Moreover, while Higgs describes the wheelchair as being foldable, he acknowledges that with electrically driven elevating devices, the battery may have to be removed prior to collapsing the wheelchair.
Despite the teachings of the prior art, a need still exists for a wheelchair which can be elevated by the individual confined in the wheelchair to a desired height and which can be mobilized by the wheelchair user while in a raised position user in a manner which is safe and practical.